This is my first post to the forum though I've come here many times seeking general advice which has been really helpful so thanks for that! My specific problem is that it seems I've thrown my tank into a cycle after medicating - I'm hoping it's only a "mini cycle" that I can regain control of without loss of life.
Here is some background--
About 1 week ago, I noticed one of my cherry barbs had a split in the tail and another had black tips on her fins. Looking closer I could see the fins of most of the c.b.'s were slightly affected. I guessed it was the start of fin rot due to poor water conditions, which was confirmed from testing as nitrates were higher than they'd ever been (80+ ppm
; ammonia 0). I suppose this was from overfeeding and/or less frequent or smaller water changes in the last few weeks. Really, I don't think there was a major change to the maintenance routine so I am still a little perplexed about why. The only other change was that I'd recently wiped down the back of the tank and also rinsed (in tank water) and wiped down tank decorations to get rid of the coating of brown algae that's been growing for a long time. Normally, I let it alone in case it disturbs the balance but it had been affecting the plants more lately and I finally got tired of looking at it. I did leave some there and didn't go crazy with it....I don't know tho - could that cause the nitrates to spike?
So back to the fin damage- First did a few water changes to lower the nitrates. At my lfs
they suggested melafix. They said to use the dosage on the instructions (10 ml/day for 7 days) and to take the carbon out. I put in a new filter bag without carbon. But because I have cardinals and I'm leery of additives in general, I stayed below the recommended dosage (more like 7 ml/day) and continued doing pwc
's every other day. I got up to Day 6 but stopped a couple of days ago when I tested and found there was ammonia, which never happens. At that point I did about a 30% change and added about 25 drops of Prime, and that seemed to fix the problem temporarily at least. Then last night, the ammonia was up again so I did a 40% change and added 40 drops of Prime. When I tested today, it looked like the ammonia was at a higher concentration again than yesterday, and there was nitrite also, which I hadn't tested for earlier. Today I put carbon back into the filter. Fishes behavior appears mostly normal - maybe somewhat more stressed than usual but they are not gasping or hiding. I am not sure if the fins have improved but they are not any worse.
I need to consult with some folks more knowledgeable than me to get some help with 2 major questions because at this point I'm starting to feel like I'm just guessing!
1) what should I do next? (should I continue trying to manage with water changes? Is it ok to keep using Prime like this? Anything else I can do)
2) why did this happen? (did melafix kill the beneficial bacteria? can removing the algae cause a nitrate spike?)
Thanks so much for reading...any and all suggestions are very much appreciated!!
Current Parameters/Additional Info:
0.50 and rising
20g long, 1 year old
8 cherry barbs (5 F/3 M - 2 of the females are massive and look like they are on steroids) and 7 cardinal tetras, nothing added in last 4-5 months
Once per week 25% water change and "quick" gravel vac. More thorough vac (removing everything) every few weeks
The amount of fish in the tank is a little more than I am comfortable with to be honest because there really isn't much room for slipping up on maintenance at all. Up to this point I haven't had any big problems or lost any fish though.